Field of the Disclosure
The present disclosure relates generally to additive manufacturing, and, more particularly, to the analysis of material performance in additively manufactured structures.
Description of the Related Art
Additive manufacturing (AM), commonly referred to as 3D printing, transforms a material into three-dimensional parts incrementally, layer by layer or path by path. This distinctive feature gives AM advantages over the traditional manufacturing techniques, such as the ability to fabricate parts with complex shapes and internal structures without a significant increase in cost or turnaround time. In many cases, a complex heterogeneous structure with less material may be both cheaper and faster to manufacture than a part with a simpler geometry and homogeneous material, such as a solid cube. This phenomenon is sometimes referred to the “complexity paradox.”
Similar to other manufacturing methods, the quality of additively manufactured parts is subject to the process limitations and machine imprecision. Due to the manufacturing process, there are various differences between the designed and the manufactured part. Fused deposition modeling (FDM) is a particular type of AM technique. An FDM tool includes a print head that extrudes a molten filament. The filament is extruded through a heated nozzle. For each layer, the nozzle moves horizontally following a piece-wise linear path. The material extruded along each line segment is commonly referred as a “road.” After each deposition, the road solidifies and bonds with adjacent roads in both current and previously deposited layers. After the whole layer is deposited, either the nozzle or the printing plate shifts vertically to print the next layer. Articles built by FDM differ noticeably from their design models due to many factors, including stair-stepping on the surface of the part, the rounding of sharp corners, air gaps, and the use of infill patterns to save the printing material and printing time for “solid” regions. In contrast to other traditional manufacturing processes, the AM material undergoes a fundamental phase transformation during the AM process, changing not only its geometry but also its mechanical properties. Processing plans and parameters in AM also play a more significant role in the final performance of the part—the same nominal part geometry manufactured with two different sets of process plans will generally result in parts with significantly different properties. As a result, AM processes lead to a heterogeneous and anisotropic distribution of material properties in the interior of the fabricated part, which is not represented and accounted for in the design model of the part. In other words, the design model is no longer a suitable surrogate for the fabricated part. The accuracy of downstream applications, such as structural analysis, relies on the ability to model not only the geometry of the manufactured part, but also its material's mechanical properties.